Cassidy tearfully resigned as deputy at Tuesday’s council meeting and minutes later held an impromptu press conference in which she dropped a bombshell: a “brief” inappropriate relationship with Brown was behind the decision.

“Over time, we developed a very close and highly productive working relationship,” Cassidy said. “Unfortunately, the relationship between the mayor and me, for a brief period of time, crossed a professional boundary.”

In a city with a long run of mayoral scandals going back 20 years, Tuesday’s dramatics set off another.

Cassidy declined to take questions, but her comments suggest she may still return as councillor for north-end Ward 5 after her leave of absence ends. Brown said he’s taking some time away from work but intends to return. Both Brown and Cassidy are married with school-age children.

In a written statement, Brown admitted to the relationship with Cassidy, calling it a “grave error in judgement on my part.”

“I can confirm what some have speculated. Over the past many months, during a period of intense workload, I developed a close working relationship and ultimately an inappropriate personal relationship . . . (with Cassidy) for a brief period of time,” he wrote, adding it “ended some time ago.”

Brown says he believes it’s “entirely possible” he and Cassidy can continue working together on council, though politics aren’t his priority at the moment.

In his statement, Brown said his wife — though “angry” over his “inappropriate personal relationship” with Cassidy — agreed to work through the matter with marriage counselling and their church’s minister.

Amid official silence throughout city hall last week, The Free Press reported Cassidy was taking a brief hiatus from her council duties to tend to a personal matter. There were quickly whispers of a Cassidy-Brown controversy.

Tuesday, Cassidy tearfully announced to her council colleagues she was quitting as deputy mayor (she’d held the post for nearly two years), but didn’t say she was leaving council altogether.

Her comments cast an unusually heavy pall over council, with some colleagues in tears.

“I’d almost like to speak . . . but I don’t think I’d be able to get through it,” an emotional Hubert said.

Her announcement was followed about 10 minutes later by the impromptu news conference just outside council chambers. Several council colleagues stood nearby as she addressed reporters.

Joe Fontana resigned as mayor in 2014 after being convicted of defrauding taxpayers when he was a London Liberal MP. The resignation rocked London and made national headlines.

Two earlier mayors were also thurst under harsh spotlights by scandal,including Anne Marie DeCicco-Best, the city’s longest-serving mayor, for a boozy, wintry drive by her husband that ended with him found guilty of impaired driving causing bodily harm.

DeCicco’s predecessor, Dianne Haskett, came under a harsh spotlight for refusing to issue a civic gay pride proclamation in the 1990s, with the Ontario Human Rights Commission ruling against her and the city and fining them for discrimination.

Brown was elected about five months after Fontana’s resignation, running, in part, on a pledge to restore integrity to the mayor’s office. Asked Tuesday whether this harms those efforts, he was straight-forward.

“I wan to be as transparent as possible,” he said. “I want to talk about this grave error that I’ve made, and I need to own that.”

Cassidy, 49, has been arguably Brown’s closest political ally, along with Hubert, especially over the past several months as council navigated its way through the oft-choppy rapid transit debate.

Brown, 42, was a teacher before being elected to council in 2010. Four years later, we was mayor. This is Cassidy’s first term on council, having been elected in a landslide in north-end Ward 5.

“I am very grateful to have such an intelligent and amazing group of people to work with,” Cassidy said to her council colleagues after announcing her resignation as deputy mayor, prompting a standing ovation from them.

Written statement from Mayor Matt Brown, released at 8:33 p.m. Tuesday:

In recent days there have been rumours circulating about my private life. Out of fairness for my colleagues and my family, I believe the best course of action is to address them directly.

I can confirm what some have speculated. Over the past many months, during a period of intense workload, I developed a close working relationship and ultimately an inappropriate personal relationship with Deputy Mayor Maureen Cassidy, for a brief period of time. This was a grave error in judgement on my part. The relationship ended sometime ago.

I am deeply sorry for the pain that this has caused – for my wife, my family and everyone involved. I make no excuses for my behavior and my poor judgement in my personal life.

Justifiably, my wife Andrea was extremely angry with me when I told her of the affair. My actions have put a tremendous strain on our relationship. Despite this, she has committed to working through this together and doing what we need to repair the damage I have caused to our marriage.

I love my wife, and we are working through our private issues together, with the help of marriage counselling and the minister of our Church, who has been a true friend to us.

I realize there will be many questions related to my personal and my professional life. In light of that, I will sit down with the integrity commissioner on Thursday. While I do not believe my relationship with the Deputy Mayor resulted in any breach of my professional responsibilities as Mayor, I nonetheless want to obtain his opinion to ensure that there are no issues. I will abide by any decisions or recommendations of the Commissioner.

I want to be as open and transparent as possible. I have made a grave error and I need to own that.

But, I also ask that members of the media and our London community respect the need of my wife and children for some privacy as we work through this difficult time.

I love my family and I love my work as mayor of London. I look forward to continuing that work over the next number of years, even as I find a better balance between the demands of my job, and the needs of my wife and family.

My primary focus must always be to earn the love and respect of Andrea and my family.

I intend to spend more time with my children and my wife in the coming weeks. I’m taking some time away over the next little while and I will return to my other duties when we’re ready.

Mayor Matt Brown, City of London

Statement from Maureen Cassidy, to reporters at city hall Tuesday after her resignation as deputy mayor:

Over the past year and a half, my work as deputy mayor has involved long hours working closely with the mayor under conditions that were frequently extremely stressful.

Over time, we developed a very close and highly productive working relationship.

Unfortunately, the relationship between the mayor and me for a brief period of time crossed a professional boundary, and this is something which I regret immensely.

I’ve caused my family horrible pain and embarrassment, and for this I could never apologize enough.

I know this has also hurt the Brown family deeply and for this I am very sorry.

I apologize as well to my council colleagues for the disruption and distress that this announcement is bound to cause for them. It was never my intention to disrespect either them as individuals or the office we hold.

I am extremely proud of my work both as city councillor and deputy mayor. I’ve always endeavoured to serve my constituents and the citizens of London to the best of my abilities. And I have always maintained a high degree of professionalism in my work.

Nothing I have done has ever compromised that.

My family and I are now working through this together. We are working together to rebuild the trust that has been broken. Thank you for respecting their privacy at this time and for understanding that for us this is a very personal matter.

I won’t be taking any questions and I won’t be issuing any further statements.

Q&A with Matt Brown:

LFP: I guess I’ll start with this: (Deputy mayor) Paul Hubert suggested he would be acting mayor Wednesday. Fair to conclude you’re taking something of a hiatus or a leave?

BROWN: I intend to spend more time with my children and my wife in the coming weeks. I’m taking some time away over the next little while and I’ll return to my duties when we’re ready.

Q: I think you have a three-month grace period (before your seat is declared vacant). You’re talking about less than three months, I guess?

A: I’m going to take the next few days with Andrea (his wife) and the boys. My primary focus will be on my family over the next little while and I’ll return to my other duties when we’re ready.

Q: So, there’s no part of you that’s even considering the possibility of resigning as mayor?

A: I love my family and I love my work as mayor of London. I do look forward to continue that work over the next number of years and I’m going to find a better balance between the demands of my job and the needs of my wife and my family.

Q: These sorts of workplace affairs, workplace relationships, this happens. What would you say to people who are sitting in judgment?

A: I’d say that I’m deeply sorry for the pain this has caused for my wife, for my family, for everyone involved. I make no excuses for my behaviour. I make no excuses for my poor judgment in my personal life.

Q: I hate to even ask this, but when you ran for office there was a lot of talk about restoring integrity to the mayor’s office. Would you agree this sets that effort back?

A: I want to be as transparent as possible. I want to talk about this grave error that I’ve made, and I need to own that. That is an important thing to do and I recognize that this is something that occurred in my personal life but I also recognize that it gets treated differently because I’m a public figure.

Q: Although it is a personal matter, it does cross into the professional arena. Can you and Maureen Cassidy still work together on council?

A: I believe that is entirely possible. My commitment first and foremost is to my family. To ensure I’m focused on repairing the damage I’ve caused in my marriage and I will continue to work in a very professional way, in a very respectful way, with all of my council colleagues.